There is known a film forming apparatus in which a plurality of wafers is mounted on a rotary table installed within a process vessel in a rotational direction of the rotary table.
The film forming apparatus includes a gas supply part installed in a diameter direction of the rotary table to supply a process gas, and a heater installed below the rotary table to heat the wafers. Further, in a state where the wafers are heated by the heater and the process gas is discharged from the gas supply part, the film forming process is performed on the wafers by rotating the rotary table. Also, in the film forming apparatus, a temperature control is performed by controlling a power supplied to the heater based on a temperature measured by a thermocouple installed near the heater.
Further, in a film forming apparatus in which a plurality of wafers is mounted on a rotary table installed within a process vessel in a rotational direction of the rotary table, there is known a technique of measuring a temperature of the rotary table or the wafer using a non-contact type temperature measuring part.
However, in the case of controlling the power supplied to the heater based on the temperature measured by the thermocouple installed near the heater, when the film forming process such as a plasma process or the like is performed on the wafers, a significant difference may occur between the temperature of the wafer and the temperature measured by the thermocouple. Such a temperature difference may occur because the wafers are exposed to plasma while the thermocouple is not exposed to plasma.
Accordingly, in the case of performing the temperature control by controlling the power supplied to the heater based on the temperature measured by the thermocouple, there is a possibility that the temperature control may not be performed with high precision.